Non-equal wasm-opt results#150

First off, thanks for the great crate and API! There are a few conformance issues though... using `OptimizationOptions::new_optimize_for_size_aggressively()` and `wasm-opt -Oz` (from the main binaryen project) do not have the same outputs. To reproduce, I wrote this program in [tinygo](https://github.com/tinygo-org/tinygo): ```go package main import "fmt" func main() { fmt.Println("hello world") } ``` In `main.go`. I compiled it with: `tinygo build -o out.wasm -target wasm main.go`. Trying to optimize for size aggressively results in different file sizes. I am on `wasm-opt` v114 and using the `0.114.0` version of this crate.